Automatic or semi-automatic rifles typically include an upper receiver and a lower receiver. The upper receiver can support a number of rifle components, for example, a barrel and sights. The lower receiver may also support and/or house other components, such as an ammunition magazine, a grip, and a trigger mechanism. The upper receiver may be pivotally attached to the lower receiver using a pivot pin. A user of the firearm may access internal rifle components by pivoting the upper receiver away from the lower receiver about the pivot pin. Access to internal rifle components may be desirable for a number of reasons, such as cleaning and maintenance. The upper receiver is typically secured to the lower receiver using a takedown pin. The takedown pin may be located opposite of the pivot pin and proximate to the aft end of the receivers. When installed, the takedown pin secures the upper receiver to the lower receiver enabling operation of the rifle.